'82 300 SD Hard to start.

[kyle300SD Turbo]

I am admitting now that I am not a MB diesel tech. but I have worked on them before and I was a ASE cert. tech before I changed my career in '97.

200,000+ miles...well maintained.
Car has been sitting for around 4 months.

The car is in Houston Texas and the outside temp. is between 40 and 60 degrees F.

Glow plugs are coming on when checked with a test light and the glow plugs have a resistance of around 2-4ohms....#1 was replaced recently.
The preglow indicator does not work on the dash but you can hear the relay click on and then off after around 1 minute and this is verified with the test light.
We did get it started after several tries but after sitting overnight it was reluctant to start up again.
It seems to run good once it's running and will start right back up when the engine is warm.
It acts like low fuel to the cylinders. Could the fuel be weak?

It does need the oil changed.

Any ideas?
Thanks in advance.